Instruction Operand Encoding

Op/En

Operand 0

Operand 1

Operand 2

Operand 3

A

NA

NA

ModRM:r/m (r)

ModRM:reg (r, w)

Description

Performs a SIMD compare of the packed unsigned byte integers in the destination operand (first operand) and the source operand (second operand), and returns the minimum value for each pair of byte integers to the destination operand. The source operand can be an MMX technology register or a 64-bit memory location, or it can be an XMM register or a 128-bit memory location. The destination operand can be an MMX technology register or an XMM register.

In 64-bit mode, using a REX prefix in the form of REX.R permits this instruction to access additional registers (XMM8-XMM15).

If the memory address is in a non-canonical form. (128-bit operations only) If memory operand is not aligned on a 16-byte boundary, regardless of segment.

#SS(0)

If a memory address referencing the SS segment is in a non-canonical form.

Compatibility Mode Exceptions

Same as for protected mode exceptions.

Virtual-8086 Mode Exceptions

Exception

Description

#AC(0)

(64-bit operations only) If alignment checking is enabled and an unaligned memory reference is made.

#PF(fault-code)

For a page fault.

Same exceptions as in real address mode.

Real-Address Mode Exceptions

Exception

Description

#MF

(64-bit operations only) If there is a pending x87 FPU exception.

#NM

If CR0.TS[bit 3] = 1.

#UD

If CR0.EM[bit 2] = 1. (128-bit operations only) If CR4.OSFXSR[bit 9] = 0. Execution of 128-bit instructions on a non-SSE2 capable processor (one that is MMX technology capable) will result in the instruction operating on the mm registers, not #UD. If the LOCK prefix is used.

#GP

(128-bit operations only) If a memory operand is not aligned on a 16-byte boundary, regardless of segment. If any part of the operand lies outside of the effective address space from 0 to FFFFH.

Protected Mode Exceptions

Exception

Description

#AC(0)

(64-bit operations only) If alignment checking is enabled and an unaligned memory reference is made while the current privilege level is 3.

#PF(fault-code)

If a page fault occurs.

#MF

(64-bit operations only) If there is a pending x87 FPU exception.

#NM

If CR0.TS[bit 3] = 1.

#UD

If CR0.EM[bit 2] = 1. (128-bit operations only) If CR4.OSFXSR[bit 9] = 0. Execution of 128-bit instructions on a non-SSE2 capable processor (one that is MMX technology capable) will result in the instruction operating on the mm registers, not #UD. If the LOCK prefix is used.

#SS(0)

If a memory operand effective address is outside the SS segment limit.

#GP(0)

If a memory operand effective address is outside the CS, DS, ES, FS, or GS segment limit. (128-bit operations only) If a memory operand is not aligned on a 16-byte boundary, regardless of segment.